1. Field of the Invention
The present invention relates to a method for determining the torque of an internal combustion engine for a motor vehicle, particularly the internal combustion engine of a motor-vehicle hybrid drive device, with the aid of at least one secondary motor, especially an electric motor, coupled to the internal combustion engine.
2. Description of Related Art
Determining the instantaneous torque of the internal combustion engine is particularly important for motor vehicles having an electronic engine management, since this value is a control variable of the internal combustion engine, and therefore has a strong influence on the performance of the motor vehicle.
Under the state of the art, the torque maps of a small number of internal combustion engines are measured during the development of a motor vehicle. The map of all internal combustion engines of an entire production run is inferred based on this data. However, due to manufacturing tolerances during the production of the internal combustion engines, deviations frequently occur between the actual, instantaneous torque present and the torque predefined by the control circuit of the internal combustion engine. These deviations have a negative effect on the performance of the motor vehicle. If, in addition to the internal combustion engine, a further secondary motor, particularly an electric motor in a motor-vehicle hybrid drive device, is provided in the drive system of the motor vehicle and coupled to the internal combustion engine, then the torque maps for the internal combustion engine and the secondary motor are recorded separately from each other, any existing errors in the torque map, particularly the torque map of the internal combustion engine, thereby adding up. In principle, however, the instantaneous torque of an electric motor may be determined from existing characteristic quantities, particularly speed and flowing current, with markedly greater accuracy than for an internal combustion engine.